1. Field of the Invention
The present invention relates to ventilators, e.g., continuous positive air pressure (“CPAP”) systems comprising a mask and an air flow generator, wherein the air flow generator is mountable to the mask's wearer. In one embodiment, the present invention provides CPAP systems wherein an air flow generator is mounted on the mask. In other embodiments, the air flow generator may be provided to the body of the wearer, e.g., the arm, leg, chest or waist, and a short air delivery tube can be used to connect the mask with the air flow generator.
2. Description of Related Art
CPAP administration is commonly used to treat respiratory conditions such as obstructive sleep apnea. The procedure for CPAP administration typically involves sealingly engaging a mask over a patient's nasal and/or oral region and supplying pressurized air to a chamber formed by the interior of the mask. In conventional systems, the air is supplied to the mask by an air flow generator typically placed in proximity to the patient's bed. An air delivery tube is thus needed to deliver air generated by the air flow generator to the mask.
There are two main sources of instability of a mask system during use or sleep. Normal patient movement can create instability, for example, a patient rolling on his or her side, which may cause the mask to interfere with the bedding material. Another concern of using an air delivery tube that is connected to an apparatus away from the patient is so-called “tubing drag”, which refers to a drag force on the air delivery tube which is draped over the back or side of the bed. Tubing drag can be created or complicated by movement of the wearer. Tubing drag may cause relative movement between the mask seal and the patient's face during the CPAP administration and produce leaks and/or discomfort.
Another concern involving the air delivery tube is the length thereof (often about 2 meters or more), which may impart a lag in the response and rise times in delivering pressured air from the air flow generator to the mask. Increased flow impedance and/or pressure drop due to diameter and length of tubing may also necessitate a larger blower motor to compensate for the pressure drop along the air delivery tube.
U.S. Pat. Nos. 4,590,951; 5,372,130; and 6,435,184 describe masks for safety applications.